Telephone line

Telephone line
Phone pole with phone and mainly electric lines
Fixed telephone lines per 100 inhabitants 1997–2007

A telephone line or telephone circuit (or just line or circuit within the industry) is a single-user circuit on a telephone communication system. Typically this refers to the physical wire or other signaling medium connecting the user's telephone apparatus to the telecommunications network, and usually also implies a single telephone number for billing purposes reserved for that user.

In 1876 the earliest lines were single electrically conducting metal wires directly connecting one telephone to another with the Earth forming the return circuit. Later in 1878 the Bell Telephone Company began to use two-wire circuits (called the local loop) from each user's telephone to end offices which performed any necessary electrical switching to allow voice signals to be transmitted to more distant telephones.

These wires were typically copper, although aluminium has also been used, and were carried in balanced pairs separated by about 25 cm (10") on poles above the ground, and later as twisted pair cables. Modern lines may run underground, and may carry analog or digital signals to the exchange, or may have a device that converts the analog signal to digital for transmission on a carrier system.

In most cases, two copper wires (tip and ring) for each telephone line run from a home or other small building to a local telephone exchange. There is a central junction box for the building where the wires that go to telephone jacks throughout the building and wires that go to the exchange meet and can be connected in different configurations depending upon the subscribed telephone service. The wires between the junction box and the exchange are known as the local loop, and the network of wires going to an exchange, the access network.

Most houses in the U.S. are wired with 6-position modular jacks with four conductors wired to the house's junction box with copper wires. Those wires may be connected back to two telephone lines at the local telephone exchange, thus making those jacks RJ14 jacks. More often, only two of the wires are connected to the exchange as one telephone line, and the others are unconnected. In that case, the jacks in the house are RJ11.

See also

External links

Wikimedia Foundation. 2010.

Игры ⚽ Нужно решить контрольную?

Look at other dictionaries:

  • Telephone Line — Single par Electric Light Orchestra extrait de l’album A New World Record Face B Poor Boy (The Greenwood) Sortie mai 1977 Enregistrement Studios Musicland (Munich) Durée …   Wikipédia en Français

  • telephone line — telephone channel, connection for a telephone …   English contemporary dictionary

  • Telephone Line (Electric Light Orchestra song) — Infobox Single Name = Telephone Line Artist = Electric Light Orchestra from Album = A New World Record B side = Poor Boy King Of The Universe (UK only) Released = 1977 Format = 7 Recorded = 1976 Musicland Studios , Munich Genre = Art rock Length …   Wikipedia

  • telephone line — noun 1. the wire that carries telegraph and telephone signals (Freq. 3) • Syn: ↑telephone wire, ↑telegraph wire, ↑telegraph line • Hypernyms: ↑wire, ↑conducting wire …   Useful english dictionary

  • telephone line — noun The infrastructure which allows a single telephone to be connected to the network and conduct independent calls …   Wiktionary

  • telephone line —    See telephone circuit …   IT glossary of terms, acronyms and abbreviations

  • telephone line — A wire, carried overhead on poles or underground in a conduit, over which articulate speech is transmitted and received. A statute defines the term as including every sort of property used, operated, controlled, or owned by any telephone… …   Ballentine's law dictionary

  • First long-distance telephone line — Infobox local1 name =World s First Long Distance Telephone Line chisl = yes caption = location= Pleasant Valley Road French Corral, California lat degrees = lat minutes = lat seconds = lat direction = long degrees = long minutes = long seconds =… …   Wikipedia

  • another telephone line — extra telephone line, additional telephone service …   English contemporary dictionary

  • Telephone recording laws — are laws that govern the civilian recording of telephone conversations by the participants (as opposed to laws controlling government or law enforcement wiretapping).Telephone tapping is officially strictly controlled in many countries to… …   Wikipedia

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”